This invention relates to a key input device applicable to electronic devices such as a personal computer, a word processor, etc., and more particularly to a key input device applicable to highly portable information terminals such as computers of a note book size, of a mini note book size smaller than the note book size, of a palm top size, etc.
The entire contents of Japanese Patent Application No. 9-135295 filed May 26, 1997 are incorporated herein by reference.
FIG. 1 shows an example of a highly portable personal computer with a key input device. In this specification, the key input device includes a keyboard with a plurality of keys and a keyboard controller for outputting a key code corresponding to a depressed key.
In the computer shown in FIG. 1, a keyboard 1 is formed integral with a computer main body 2. The keyboard 1 is electrically connected, via a keyboard controller for outputting a key code corresponding to a depressed key, to internal units built in the main body 2, for example, main unit including a CPU (Central Processing Unit) and peripheral units such as an HDD (Hard Disk Drive), a CD-ROM (Compact Disk Read Only Memory) drive, etc.
The keyboard 1 has substantially rectangular data keys 1a including character keys, numeral keys and code keys, substantially rectangular control keys (hatched keys in FIG. 1) 1b including an "Enter" key, a "Home" key, etc., and function keys 1c for effecting predetermined functions.
The data keys 1a are linearly arranged in rows. The data key rows are arranged in slanted columns such that they deviate from each other at a predetermined pitch in the row direction. The data keys 1a arranged as above are put substantially between the control keys 1b, and a space bar included in the data keys 1a is put between some of the control keys 1b. More specifically, the control keys 1b-1 to 1b-4 indicate the "Home" key with a function for moving the cursor to a leftmost row position, an "End" key with a function for moving the cursor to a rightmost row position, a "PgUp" key with a function for returning the cursor by one page, and a "PgDn" key with a function for advancing the cursor by one page, respectively. The function keys 1c are arranged in the uppermost row of the keyboard 1. Further, the above keys are arranged to meet a predetermined standard such as the ASCII.
FIGS. 2 and 3 show examples of the keyboard 1 with the above-described key arrangement. FIG. 2 shows a key arrangement for USA, while FIG. 3 shows a key arrangement for Europe. The overall key arrangement of each of FIGS. 2 and 3 is similar to that of FIG. 1. However, sign assignments to the data keys 1a slightly differs between FIGS. 2 and 3, since frequency in use of each sign differs among different countries. Furthermore, the length of the space bar differs since the number of data keys la differs. In each of the key arrangements, however, the control keys 1b-1 to 1b-4 are arranged at a right end portion of the keyboard.
Recently, more compact and hence more portable personal computers have been developed. In accordance with the development, it is necessary to further reduce the sizes of the keyboard 1 and each key thereof. The size of each key is generally represented by the distance (key pitch) between the center points of adjacent data keys. To meet the recent demand for reduction of the keyboard size, the key pitch may become 13 mm or less if the same number of keys as in the conventional case should be arranged on the keyboard. Where the key pitch is that small, the operability of the keys may well reduce, resulting in erroneous operation of the computer.